Ink compositions

ABSTRACT

Polyurethanes containing at least one bisphosphonate group, as well as related compositions, articles, and methods, are disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national phase application under 35 U.S.C. §371 ofInternational Application Number PCT/US2011/056985, filed on Oct. 20,2011, which claims priority to U.S. Provisional Patent Application No.61/405,796, filed on Oct. 22, 2010, the disclosure of which isincorporated herein by reference.

TECHNICAL FIELD

This disclosure relates to polyurethanes containing at least onebisphosphonate group, as well as related compositions, articles, andmethods.

BACKGROUND

Ink compositions generally contain water soluble dyes or water-insolublepigments. Although some dye-based inks are suitable for their intendedpurposes, dyes have several disadvantages when used in inkjet inkcompositions. For example, water-soluble dyes may dissolve and run whenexposed to moisture or water. Dye images may further smear or rub off oncontact with felt pen markers or upon being rubbed or touched by finger.Dyes may also exhibit poor light stability when exposed to visiblelight, ultraviolet light, or sunlight. Pigments can also be used ascolorants in ink compositions to overcome some of the disadvantages ofthe dyes.

SUMMARY

The inventors have realized that certain polymers (e.g., polyurethanes)containing at least one bisphosphonate group can be used as an additiveor dispersant in an ink composition (e.g., an inkjet ink composition) toimprove the jetting of the composition. In addition, images generatedfrom such an ink composition can have improved optical density and/orimproved durability (e.g., with little or no trail in a highlight smeartest).

In one aspect, this disclosure features a polyurethane including a firstcomonomer repeat unit that contains a hydrophilic group. Thepolyurethane further includes a functional group different from thehydrophilic group. The functional group contains (CH₂)_(n)C(R)(PO₃H₂)₂or an ester or salt thereof, in which n is 0-9 and R is H, R_(a),OR_(a), SR_(a), or NR_(a)R_(b), each of R_(a) and R_(b), independently,being H, C₁-C₁₀ alkyl, or aryl.

In another aspect, this disclosure features a polyurethane containing afunctional group as an end group of the polyurethane. The functionalgroup includes (CH₂)_(n)C(R)(PO₃H₂)₂ or an ester or salt thereof, inwhich n is 0-9 and R is H, R_(a), OR_(a), SR_(a), or NR_(a)R_(b), inwhich each of R_(a) and R_(b), independently, is H, C₁-C₁₀ alkyl, oraryl.

In another aspect, this disclosure features a polyurethane that includesa comonomer repeat unit of formula (IV) or (V):N(R₉)—R₄—N(R₆)—R₅—N(R₁₀)—  (IV)or—N(R₉)—R₄—C(R₇R₈)—R₅—N(R₁₀)—  (V)in which each of R₄ and R₅, independently, is a bond, C₁-C₁₀ alkylene,C₃-C₂₀ cycloalkylene, C₃-C₂₀ heterocycloalkylene, arylene, orheteroarylene, each of which being optionally substituted with C₁-C₁₀alkyl or aryl, provided that at least one of R₄ and R₅ is not a bond; R₆is (CH₂)_(n)C(R)(PO₃H₂)₂ or an ester or salt thereof, in which n is 0-9and R is H, R_(a), OR_(a), SR_(a), or NR_(a)R_(b), each of R_(a) andR_(b), independently, being H, C₁-C₁₀ alkyl, or aryl; each of R₇ and R₈,independently, is H, R_(c), OR_(c), SR_(c), NR_(c)R_(d), PO₃H₂ or anester or salt thereof, or (CH₂)_(m)C(R′)(PO₃H₂)₂ or an ester or saltthereof, in which m is 0-9 and R′ is H, R_(c), OR_(c), SR_(c), orNR_(c)R_(d), each of R_(c) and R_(d), independently, being H, C₁-C₁₀alkyl, or aryl, provided that, if neither of R₇ and R₈ is(CH₂)_(m)C(R′)(PO₃H₂)₂ or an ester or salt thereof, both of R₇ and R₈are PO₃H₂ or an ester or salt thereof; and each of R₉ and R₁₀,independently, is H, C₁-C₁₀ alkyl, or aryl.

As used herein, the term “alkyl” refers to a saturated, linear orbranched, non-cyclic hydrocarbon moiety, such as —CH₃ or —CH(CH₃)₂. Theterm “alkylene” refers to a divalent alkyl. The term “cycloalkyl” refersto a saturated, cyclic hydrocarbon moiety, such as cyclohexyl. The term“cycloalkylene” refers to a divalent cycloalkyl. The term“heterocycloalkyl” refers to a saturated, cyclic moiety having at leastone ring heteroatom (e.g., N, O, or S), such as 4-tetrahydropyranyl. Theterm “heterocycloalkylene” refers to a divalent heterocycloalkyl. Theterm “aryl” refers to a hydrocarbon moiety having one or more aromaticrings. Examples of aryl moieties include phenyl (Ph), naphthyl, pyrenyl,anthryl, and phenanthryl. The term “arylene” refers to a divalent aryl(e.g., phenylene or naphthylene). The term “heteroaryl” refers to amoiety having one or more aromatic rings that contain at least oneheteroatom (e.g., N, O, or S). Examples of heteroaryl moieties includefuryl, furylene, fluorenyl, pyrrolyl, thienyl, oxazolyl, imidazolyl,thiazolyl, pyridyl, pyrimidinyl, quinazolinyl, quinolyl, isoquinolyl andindolyl. The term “heteroarylene” refers to a divalent heteroaryl.

In still another aspect, this disclosure features a composition (e.g.,an ink composition) containing one or more of the polyurethanesdescribed above and a liquid vehicle.

Other features and advantages will be apparent from the description andthe claims.

DETAILED DESCRIPTION

This disclosure generally relates to compositions (e.g., inkcompositions) containing a polyurethane having at least onebisphosphonate group. The composition can have improved jetting propertyand can generate images with improved optical density and durability(e.g., with little or no trail in a highlight smear test).

As used herein, the term “polyurethane” refers to a polymer containingorganic moieties joined by urethane (e.g., —NH—C(O)—O—) linkages. Insome embodiments, the polyurethane described herein can also includeother types of linkages, such as urea linkages (e.g., —NH—C(O)—NH—), inaddition to the urethane linkages. Such polymers are still referred toas polyurethanes in this disclosure.

In some embodiments, the polyurethane includes at least a firstcomonomer repeat unit that contains one or more hydrophilic groups. Asused herein, the term “hydrophilic group” refers to a group capable offorming hydrogen bonding with water. Exemplary hydrophilic group includea hydroxyl group, a carboxylic acid group, a sulfonic acid group, aphosphonic acid group, a polyether group (e.g., a polyethylene glycolgroup), and a salt thereof. The hydrophilic group can be either ionic(e.g., a carboxylic acid group) or non-ionic (e.g., a hydroxyl group).

The polyurethane can further include a functional group (e.g., a moietycontaining a bisphosphonate group) different from the hydrophilic group.As used herein, the term “bisphosphonate group” refers to any moietycontaining two phosphonic acid groups (i.e., PO(OH)₂) or an ester orsalt thereof. In some embodiments, a bisphosphonate group can be amoiety containing two phosphonic acid groups (i.e., PO(OH)₂) or an esteror salt thereof on the same carbon atom. The functional group can belocated on the first comonomer repeat unit or on a comonomer repeat unitdifferent from the first comonomer repeat unit. Examples of comonomerrepeat units containing the functional group include comonomer repeatunits of formulae (VI) and (V) described below. In such embodiments, thefunctional group is typically located in the middle of the polymer chainof the polyurethane.

In some embodiments, the functional group can be an end group of thepolyurethane. In such embodiments, the functional group can be locatedeither at only one end of the polyurethane or at both ends of thepolyurethane.

In some embodiments, the functional group can include(CH₂)_(n)C(R)(PO₃H₂)₂ or an ester or salt thereof, in which n is 0-9(i.e., 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9) and R is H, R_(a), OR_(a),SR_(a), or NR_(a)R_(b), each of R_(a) and R_(b), independently, being H,C₁-C₁₀ alkyl, or aryl. As used herein, the term “an ester or salt of(CH₂)_(n)C(R)(PO₃H₂)₂” includes both a partial ester or salt (i.e., notmore than three of the OH groups in (CH₂)_(n)C(R)(PO₃H₂)₂ have beenconverted to an ester or salt) and a complete ester or salt (i.e., allfour OH groups in (CH₂)_(n)C(R)(PO₃H₂)₂ have been converted to an esteror salt). In some embodiments, the functional group can include(CH₂)₃C(OH)(PO₃H₂)₂ or a partial ester or salt thereof.

When the functional group is a salt of (CH₂)_(n)C(R)(PO₃H₂)₂, the saltcan include an anion formed from (CH₂)_(n)C(R)(PO₃H₂)₂ (e.g.,(CH₂)₃C(OH)(PO₃H₂)(PO(OH)(O⁻))) and any suitable cation. Exemplarycations include Li⁺, Na⁺, K⁺, Cs⁺, and N(R_(c))₄ ⁺, in which R_(c) canbe H, C₁-C₁₀ alkyl, or aryl. For example, the functional group can be apartial salt containing K⁺ and an anion formed from(CH₂)_(n)C(R)(PO₃H₂)₂, such as (CH₂)₃C(OH)(PO₃H₂)(PO(OH)(OK)) or(CH₂)₃C(OH)(PO(OH)(OK))(PO(OH)(OK)). When a salt molecule contains twoor three cations (e.g., K⁺ cations), the cations can form ionic bondswith any two or three of the four OH groups in the functional group.

When the functional group is an end group of the polyurethane, thefunctional group can be introduced to the polyurethane by reacting thepolyurethane or its prepolymer with an end-capping reagent. Examples ofsuitable end-capping reagents include those of the formulaNH₂(CH₂)_(n)C(R)(PO₃H₂)₂, in which n is 0-9 (i.e., 0, 1, 2, 3, 4, 5, 6,7, 8, and 9) and R is H, R_(a), OR_(a), SR_(a), or NR_(a)R_(b), each ofR_(a) and R_(b), independently, being H, C₁-C₁₀ alkyl, or aryl. Anexemplary end-capping reagent is

(i.e., sodium alendronate).

In some embodiments, the functional group can be located in the middleof the polymer chain of the polyurethane. In such embodiments, thefunctional group can be located in a comonomer repeat unit. Examples ofsuch comonomer repeat units include comonomer repeat units of formulae(IV) and (V):—N(R₉)—R₄—N(R₆)—R₅—N(R₁₀)—  (IV)or—N(R₉)—R₄—C(R₇R₈)—R₅—N(R₁₀)—  (V)in which each of R₄ and R₅, independently, is a bond, C₁-C₁₀ alkylene,C₃-C₂₀ cycloalkylene, C₃-C₂₀ heterocycloalkylene, arylene, orheteroarylene, each of which being optionally substituted with C₁-C₁₀alkyl or aryl, provided that at least one of R₄ and R₅ is not a bond; R₆is (CH₂)_(n)C(R)(PO₃H₂)₂ or an ester or salt thereof, in which n is 0-9and R is H, R_(a), OR_(a), SR_(a), or NR_(a)R_(b), each of R_(a) andR_(b), independently, being H, C₁-C₁₀ alkyl, or aryl; each of R₇ and R₈,independently, is H, R_(c), OR_(c), SR_(c), NR_(c)R_(d), PO₃H₂ or anester or salt thereof, or (CH₂)_(m)C(R′)(PO₃H₂)₂ or an ester or saltthereof, in which m is 0-9 and R′ is H, R_(c), OR_(c), SR_(c), orNR_(c)R_(d), each of R_(c) and R_(d), independently, being H, C₁-C₁₀alkyl, or aryl, provided that, if neither of R₇ and R₈ is(CH₂)_(m)C(R′)(PO₃H₂)₂ or an ester or salt thereof, both of R₇ and R₈are PO₃H₂ or an ester or salt thereof; and each of R₉ and R₁₀,independently, is H, C₁-C₁₀ alkyl, or aryl. In formula (V), when both ofR₇ and R₈ are PO₃H₂ or an ester or salt thereof, C(R₇R₈) contains abisphosphonate group and corresponds to the functional group describedabove.

The comonomer repeat units of formulae (IV) and (V) can be prepared byusing a diamine comonomer of the formulae NH₂—R₄—N(R₆)—R₅—NH₂ andNH₂—R₄—C(R₇R₈)—R₅—NH₂, respectively. An exemplary comonomer that can beused to prepare the comonomer repeat unit of formula (IV) is

An exemplary comonomer that can be used to prepare the comonomer repeatunit of formula (V) is

The comonomer repeat units of formulae (IV) and (V) can be incorporatedinto the polyurethane by reacting a diamine comonomer with adiisocyanate (such as those described below) to form a polyurea segment(e.g., a segment containing a —NH—C(O)—NH— linkage).

In general, the polyurethane described herein can include a sufficientlylarge amount of the functional group described above. For example, whenthe functional group is measured based on the content of phosphorouscontained therein, the polyurethane can include at least about 0.1 wt %(e.g., at least about 0.2 wt %, at least about 0.3 wt %, at least about0.5 wt %, at least about 1 wt %, or at least about 5 wt %) and/or atmost about 20 wt % (e.g., at most about 15 wt %, at most about 10 wt %,at most about 5 wt %, at most about 1 wt %, or at most about 0.5 wt %)phosphorus. Without wishing to be bound by theory, it is believed that,a polyurethane containing a large amount of the functional group canhave a significantly increased acid number. Such a polyurethane, whenused in an ink composition, can greatly improve the jetting property ofthe ink composition (e.g., consistently allowing a sufficiently largeamount of the ink composition (such as more than 30 ng per ink droplet)to be ejected from an inkjet printer nozzle during printing).

In some embodiments, the first comonomer repeat unit is of formula (I):—O—R₁—O—  (I),in which R₁ is C₁-C₁₀ alkylene, C₃-C₂₀ cycloalkylene, C₃-C₂₀heterocycloalkylene, arylene, heteroarylene, or C₁-C₂₀ alkylarylene,each of which is substituted with at least one of the hydrophilic groupsdescribed above and optionally further substituted with C₁-C₁₀ alkyl oraryl. For example, R₁ can be C₁-C₁₀ alkylene substituted with acarboxylic acid (such as CH₂C(R)(COOH)CH₂ in which R can methyl, ethylor propyl) or a salt thereof.

The first comonomer repeat unit of formula (I) can generally be formedfrom a diol monomer of the formula HO—R₁—OH, in which R₁ is definedabove. For example, when R₁ is CH₂C(CH₃)(COOH)CH₂, the first comonomerrepeat unit is formed by using

(i.e., dihydroxymethylpropionic acid) as a comonomer. As anotherexample, when R₁ is CH₂C(CH₂CH₃)(COOH)CH₂, the first comonomer repeatunit is formed by using

(i.e., dihydroxymethylbutanoic acid) as a comonomer.

The polyurethane described herein can include a sufficiently largeamount of the first comonomer repeat unit. For example, the firstcomonomer repeat unit can be at least about 1% (e.g., at least about 2%,at least about 3%, at least about 5%, at least about 10%, or at leastabout 20%) and/or at most about 50% (e.g., at most about 40%, at mostabout 30%, at most about 20%, or at most about 10%) of the total weightof the polyurethane. Without wishing to be bound by theory, it isbelieved that including a sufficiently large amount of the firstcomonomer repeat unit can significantly increase the acid number of thepolyurethane, which can greatly improve the jetting property of an inkcomposition containing such a polyurethane.

In some embodiments, when the polyurethane contains a sufficient amountof the functional group described above, the first comonomer repeat unitcan be omitted from the polyurethane.

The polyurethane described herein can further include a second comonomerrepeat unit of formula (II):—C(O)—NH—R₂—NH—C(O)—  (II),in which R₂ is C₁-C₁₀ alkylene, C₃-C₂₀ cycloalkylene, C₃-C₂₀heterocycloalkylene, arylene, heteroarylene, or a combination thereof,each of which is optionally substituted with C₁-C₁₀ alkyl or aryl. Forexample, R₂ can be hexamethylene, phenylene optionally substituted withmethyl, cyclohexylene optionally substituted with methyl,

In general, the second comonomer repeat unit of formula (II) can beformed from a diisocyanate monomer of the formula OCN—R₂—NCO, in whichR₂ is defined above. Exemplary diisocyanate monomers that can be used toform the second comonomer repeat unit include toluene 2,4-diisocyanate(2,4-TDI), toluene 2,6-diisocyanate (2,6-TDI), hexamethylenediisocyanate (HDI), 4,4′-methylene diphenyl diisocyanate (4,4′-MDI),2,4′-methylene diphenyl diisocyanate (2,4′-MDI), 2,2′-methylene diphenyldiisocyanate (2,2′-MDI), methylene bis(4-cyclohexyl diisocyanate)(HDMI), m-tetramethylxylene diisocyanate (m-TMXDI), and isophoronediisocyanate (IPDI).

The polyurethane described herein can include a sufficiently largeamount of the second comonomer repeat unit. In general, the molar ratiobetween the second comonomer repeat unit and the comonomer repeat unitderived from a diol (and a diamine, if used) in the polyurethane canrange from about 1:1 to about 2:1. The weight percentage of the secondcomonomer repeat unit can range from at least about 3% (e.g., at leastabout 10) to at most about 50% (e.g., at most about 30%) of thepolyurethane, depending on the molecular weights of the diisocyanate anddiol monomers (and diamine monomers, if desired) used to formed thepolyurethane.

The polyurethane described herein can further include a third comonomerrepeat unit of formula (III):—O—R₃—O—  (III),in which R₃ can include C₁-C₁₀ alkylene, C₃-C₂₀ cycloalkylene, C₃-C₂₀heterocycloalkylene, arylene, heteroarylene, a polyether moiety (e.g., apolypropylene glycol moiety, a polytetramethyleneoxide moiety, or apolycaprolactone moiety), a polyester moiety (e.g., a poly(butyleneadipate) moiety or a poly(hexamethylene adipate) moiety), apolycarbonate moiety (e.g., a polycarbonate moiety prepared from2-butyl-2-ethylpropyl diol (such as that in the OXYMER series ofproducts available from the Perstorp Group) or a polycarbonate moietyprepared from a mixture of 1,5-pentanediol and 1,6-hexanediol (such asthat in the DURANOL series of products available from Asahi KaseiChemical Corporation)), a polyacetal moiety, a polythioether moiety, apolyester amide moiety, a polyacrylate moiety, a polyolefin moiety, apolyalkylsiloxane moiety, or a mixture thereof.

The third comonomer repeat unit of formula (III) can generally be formedfrom a diol monomer of the formula HO—R₃—OH, in which R₃ is definedabove. Exemplary diol monomers that can be used to form the thirdcomonomer repeat unit include poly(propylene glycol),polytetramethyleneoxide diol, poly(butylene adipate) glycol,poly(hexamethylene adipate) diol, polycarbonate diol prepared fromsubstituted or unsubstituted C₁-C₁₀ alkylene diols (e.g.,1,6-hexanediol, 1,5-pentanediol, or 2-butyl-2-ethylpropyl diol). Thenumber-average molecular weight of a diol monomer of the formulaHO—R₃—OH above can be from about 400 g/mol to about 6,000 g/mol (such asabout 700 g/mol to about 2,000 g/mol). Such molecular weight can bedetermined by an end group analysis. As an example, a polycarbonate diolprepared from 1,5-pentanediol can have the following formula:H(OCH₂CH₂CH₂CH₂CH₂OC(O))_(n)OCH₂(CH₂)₃CH₂OH. As another example,polycarbonates containing hydroxyl groups include products obtained fromthe reaction of diols (such as propanediol, butanediol, hexanediol,diethylene glycol, triethylene glycol, or tetraethylene glycol) withphosgene, diarylcarbonates (such as diphenylcarbonate) or with cycliccarbonates (such as ethylene or propylene carbonate). In addition,polycarbonates can be obtained from the reaction between a polyesterdiol and phosgene, diaryl carbonates, or cyclic carbonates.

In general, the amount of the third comonomer repeat unit in thepolyurethane described herein can vary as desired. The weight percentageof the third comonomer repeat unit can range from at least about 30%(e.g., at least about 40%) to at most about 95% (e.g., at most about90%), depending on, e.g., the molecular weights of the diisocyanate anddiol monomers used to formed the polyurethane and the reagentscontaining the functional group described above.

In some embodiments, when the polyurethane contains a sufficient amountof the first comonomer repeat unit, the third comonomer repeat unit canbe omitted from the polyurethane.

When the polyurethane contains the first, second, and third comonomerrepeat units and a function group as an end group, the polyurethane canhave the following formula:

in which n, R, and R₁-R₃ are defined above, and each of x and y can beany integer ranging from 0-100. When the polyurethane contains thefirst, second, third, and fourth comonomer repeat units, thepolyurethane can have the following formula:

in which n, R, and R₁-R₁₀ are defined above, and each of x, y, and z canbe any integer ranging from 0-100. When the polyurethane contains thefirst, second, third, and fifth comonomer repeat units, the polyurethanecan have the following formula:

in which n, R, R₁-R₅, and R₇-R₁₀ are defined above, and each of x, y,and z can be any integer ranging from 0-100.

In general, the polyurethane described herein can have a relative largeacid number. For example, the polyurethane can have an acid number of atleast about 25 (e.g., at least about 30, at least about 35, at leastabout 40, at least about 45, or at least about 50) and/or at most about200 (e.g., at most about 150, at most about 120, at most about 90, atmost about 85, at most about 80, at most about 75, or at most about 70).Typically, the polyurethane has an acid number ranging from about 32 toabout 64. Without wishing to be bound by theory, it is believed thatusing a polyurethane having a large acid number in an ink compositioncan improve the jetting property of the ink composition.

In general, the polyurethane described herein can have a suitablemolecular weight. For example, the polyurethane can have a weightaverage molecular weight of at least about 10,000 g/mol (e.g., at leastabout 15,000 g/mol, at least about 20,000 g/mol, at least about 25,000g/mol, at least about 30,000 g/mol) and/or at most about 150,000 g/mol(e.g., at most about 100,000 g/mol, at most about 80,000 g/mol, at mostabout 60,000 g/mol, at most about 40,000 g/mol). Typically, thepolyurethane has a weight average molecular weight ranging from about16,000 g/mol to about 75,000 g/mol. Without wishing to be bound bytheory, it is believed that an ink composition containing a polyurethanedescribed herein having a relatively low weight molecular weight (e.g.,less than about 50,000 g/mol or less than about 30,000 g/mol) couldresult in images with improved durability. For example, images generatedfrom such an ink composition can have little or no trail in a highlightsmear test. Further, without wishing to be bound by theory, it isbelieved that, if the weight average molecular weight of thepolyurethane is too large, the jetting capability of the ink compositioncontaining such a polyurethane would be reduced.

Without wishing to be bound by theory, it is believed that, in someembodiments, an ink composition that includes a polyurethane containinga bisphosphonate group (and/or having a suitable acid number and/or asuitable weight average molecular weight) has a jetting property similarto or better than an ink composition including a similar polyurethanewithout a bisphosphonate group. In addition, the former ink compositioncan generate images with superior durability (e.g., with little or notrail in a highlight smear test) and/or optical density compared to theimages generated by the latter composition. In certain embodiments, anink composition containing a polyurethane described herein can have asuperior jetting property and is still capable of generating images withsuperior optical density and durability. Further, without wishing to bebound by theory, it is believed that, when an ink composition describedherein is used to print an image on a substrate (e.g., paper) containingmultivalent cations (e.g., Ca²⁺), which can be either present in thesubstrate before the printing or added to the substrate after theprinting, the bisphosphonate group can interact with the multivalentcations and therefore substantially improve the image durability.

The polyurethane described herein can be made by methods known in theart, such as polycondensation reactions. The preparation typicallyinvolves multi-step synthetic processes. For example, a NCO-terminatedprepolymer can be prepared by reacting a diol monomer containinghydrophilic group of the formula HO—R₁—OH (e.g., dihydroxymethylpropionic acid), a diisocyanate monomer of the formula OCN—R₂—NCO (e.g.,a TDI), and a diol monomer of the formula HO—R₃—OH (e.g., polypropyleneglycol), in which R₁-R₃ are defined above. The preparation of such aprepolymer can occur without any solvent or within a water-miscibleorganic solvent (e.g., acetone or N-methylpyrrolidone) that do not reactwith an isocyanate group. The preparation can be carried out optionallyat an elevated temperature (e.g., at least about 50° C.) and/or in thepresence of a catalyst (e.g., dibutyl tin dilaurate). The reaction timecan range from a few minutes to a number of hours, and can depend onfactors such as reaction temperature, concentrations of the monomers,reactivity of the monomers, and the presence or absence of a catalyst.The molar amounts of all monomers involved in the preparation ofNCO-terminated prepolymer are normally selected based upon the ratioA/B, where A is the molar amount of isocyanate groups and B is the molaramount of the hydroxyl groups from all diol monomers (or diaminemonomers, if used). The ratio A/B can range from at least about 1.0(e.g., at least about 1.06) to at most about 2.0 (e.g., at most about1.6). The NCO-terminated prepolymer thus obtained can have an isocyanatecontent (i.e., NCO %) of about 0.4% to about 20% based on the weight ofthe prepolymer.

After the preparation of a desired NCO-terminated prepolymer, apolyurethane containing a bisphosphonate group as an end group can beformed by a subsequent chain extension reaction of the prepolymer in thepresence of an aqueous solution containing water and an end-cappingagent having bisphosphonate groups

The time for adding the aqueous solution can be controlled based uponthe reaction conditions (e.g., reaction temperature and pH). During theend-capping reaction, the prepolymer solution can be optionally dilutedwith one of the water-miscible organic solvents described above if theviscosity of the prepolymer solution is too high. In some embodiments,the molar percentage of the terminal isocyanate that reacts with theend-capping reagent can be from about 20% to about 40%. Any isocyanategroups that are not reacted with an end-capping reagent typically reactwith water, which functions as a chain extender and extends the chain ofthe prepolymer. Depending on the efficiency of the end-capping reaction,the composition thus formed can include polyurethane molecules withoutany bisphosphonate group, polyurethane molecules with one bisphosphonategroup, or polyurethane molecules with two bisphosphonate groups. Thiscomposition can be mixed with a pigment and a liquid vehicle to form anink composition without further purification. Optionally, suchcomposition can be purified to remove impurities and other undesirablespecies using any suitable method known in the art, such asultrafiltration/diafiltration using a membrane, reverse osmosis, and/orion exchange. Such a purified composition can then be mixed with apigment and a liquid vehicle to form an ink composition.

As another example, a polyurethane containing a bisphosphonate group inthe middle of its polymer chain can be prepared in a manner similar tothat described above except that the end-capping reagent is replacedwith a diamine comonomer of the formula —N(R₉)—R₄—N(R₆)—R₅—N(R₁₀)— (IV)or —N(R₉)—R₄—C(R₇R₈)—R₅—N(R₁₀)— (V) (e.g., dissolved in an aqueoussolution). Such a diamine comonomer can act as a polymer chain extenderand can further react with the isocyanate-terminated prepolymer to forma polyurethane containing a bisphosphonate group in the middle of thepolymer chain.

In some embodiments, when the first comonomer containing acidic groupsis used to make the polyurethane, neutralizing agents for converting theacid groups to salts can be used. Such neutralizing agents can includetertiary amines, alkali metal hydroxyl, and ammonia. Exemplary cationsformed by this neutralization reaction include Li⁺, Na⁺, K⁺, Cs⁺, andN(R_(c))₄ ⁺, in which R_(c) can be H, C₁-C₁₀ alkyl, or aryl.Neutralization can be performed at any suitable point during thepreparation of the polyurethane, e.g., either before, during, or afterthe chain extension reaction of the NCO-terminated prepolymer.

In general, the polyurethane described herein can be included in an inkcomposition either as an additive or as a dispersant.

When the polyurethane is included in an ink composition as an additive,the polyurethane typically ranges from at least about 0.1% (e.g., atleast about 0.25%, at least about 0.5%, at least about 1%, or at leastabout 2%) to at most about 10% (e.g., at most about 5%, at most about4%, or at most about 3%) of the total weight of the ink composition. Insuch embodiments, the ink composition can either include a separatedispersant to disperse the pigment in the composition or include aself-dispersing pigment (e.g., a pigment modified with a dispersant). Insuch embodiments, the polyurethane is typically not substantiallyattached (either physically or chemically) to the pigment in the inkcomposition.

When the polyurethane is included in an ink composition as a dispersant,the polyurethane typically ranges from at least about 1% (e.g., at leastabout 1%, at least about 3%, at least about 5%, at least about 6%, atleast about 7%, at least about 8%, or at least about 9%) to at mostabout 15% (e.g., at most about 14%, at most about 13%, at most about12%, or at most about 11%) of the total weight of the ink composition.In such embodiments, the composition can include a pigment (e.g., anunmodified pigment) that cannot be dispersed in an ink composition byitself. In such embodiments, at least some of the molecules of thepolyurethane are attached (either physically or chemically) to thepigment in the ink composition. The ink composition can also include oneor more dispersants in addition to the polyurethane.

The composition described herein can optionally include a pigment.Examples of suitable pigments include blue pigments, black pigments(e.g., carbon black), brown pigments, cyan pigments, green pigments,white pigments, violet pigments, magenta pigments, red pigments, yellowpigments, orange pigments, or mixtures thereof. Examples of blackpigments include various carbon blacks (e.g., Pigment Black 7) such aschannel blacks, furnace blacks, gas blacks, and lamp blacks.Commercially available black pigments include, for example, carbonblacks sold under as REGAL, BLACK PEARLS, ELFTEX, MONARCH, MOGUL, andVULCAN trademarks available from Cabot Corporation (such as BLACK PEARLS2000, BLACK PEARLS 1400, BLACK PEARLS 1300, BLACK PEARLS 1100, BLACKPEARLS 1000, BLACK PEARLS 900, BLACK PEARLS 880, BLACK PEARLS 800, BLACKPEARLS 700, BLACK PEARLS 570, BLACK PEARLS L, ELFTEX 8, MONARCH 1400,MONARCH 1300, MONARCH 1100, MONARCH 1000, MONARCH 900, MONARCH 880,MONARCH 800, MONARCH 700, REGAL 660, MOGUL L, REGAL 330, REGAL 400,VULCAN P). Carbon blacks available from other suppliers can also beused. Suitable classes of pigments include, for example, anthraquinones,phthalocyanine blues, phthalocyanine greens, diazos, monoazos,pyranthrones, perylenes, heterocyclic yellows, quinacridones, and(thio)indigoids. Examples of phthalocyanine blues include copperphthalocyanine blue and derivatives thereof (Pigment Blue 15). Examplesof quinacridones include Pigment Orange 48, Pigment Orange 49, PigmentRed 122, Pigment Red 192, Pigment Red 202, Pigment Red 206, Pigment Red207, Pigment Red 209, Pigment Violet 19 and Pigment Violet 42. Examplesof anthraquinones include Pigment Red 43, Pigment Red 194 (PerinoneRed), Pigment Red 216 (Brominated Pyrathrone Red) and Pigment Red 226(Pyranthrone Red). Examples of perylenes include Pigment Red 123(Vermillion), Pigment Red 149 (Scarlet), Pigment Red 179 (Maroon),Pigment Red 190 (Red), Pigment Violet, Pigment Red 189 (Yellow ShadeRed) and Pigment Red 224. Examples of thioindigoids include Pigment Red86, Pigment Red 87; Pigment Red 88, Pigment Red 181, Pigment Red 198,Pigment Violet 36, and Pigment Violet 38. Examples of heterocyclicyellow include Pigment Yellow 117 and Pigment Yellow 138. Other suitableexamples of pigments include Pigment Yellow 1, 74, 155, 180, 185, 213,218, 220, and 221, Pigment Red 254, and 269, and Pigment Blue 16 and 60.Examples of other suitable colored pigments are described, for example,in Colour Index, 3rd edition (The Society of Dyers and Colourist, 1982),and U.S. Application Publication Nos. 2007/0100023 and 2007/0100024.

Typically, the pigment can be at least about 0.5% (e.g., at least about1%, at least about 2%, at least about 3%, or at least about 4%) and/orat most about 30% (e.g., at most about 20%, at least about 10%, at mostabout 8%, or at most about 6%) of the total weight of an inkcomposition.

The polyurethane and pigment described above can be mixed with a liquidvehicle to form an ink composition (e.g., a flexographic ink compositionor an inkjet ink composition) by using methods well known in the art.The liquid vehicle can be a solution, a dispersion, a slurry, or anemulsion. The liquid vehicle can be an aqueous medium containing water(e.g., deionized or distilled water) or non-aqueous medium containing anorganic solvent (e.g., an alcohol). For example, the amount of water oran organic solvent in an ink composition can range from at least about60% (e.g., at least about 70%) to at most about 95% (e.g., at most about90%) based on the weight of the ink composition. An inkjet inkcomposition can include the polyurethane and pigment described herein,and an aqueous vehicle (e.g., water or a water-containing mixture).

An ink composition can include suitable additives (e.g., humectants,biocides, binders, drying accelerators, penetrants, antifoaming agents,or surfactants) to impart certain desired properties while maintainingthe stability of the compositions. For example, a humectant can be addedto reduce the rate of evaporation of water in an ink composition tominimize print head nozzle clogging. If the ink composition begins todry out, the humectant concentration increases and evaporation decreasesfurther. Humectants can also affect other properties of the inkcomposition and the printed images made therefrom, such as viscosity,pH, surface tension, optical density, and print quality. Such humectantstypically include ethylene glycol, propylene glycol, diethylene glycols,glycerine, dipropylene glycols, polyethylene glycols, polypropyleneglycols, alkane diols, amides, ethers, carboxylic acids, esters,alcohols, organosulfides, organosulfoxides, sulfones, alcoholderivatives, 3-pyrrolidone, ether derivatives, amino alcohols, andketones. The amount of a particular additive will vary depending on avariety of factors including the molecular weight of the polymers, theviscosity, the amount of any ammonium salt added, as well as the natureof the polymers, the nature of any organic groups attached to thepigment.

A printed image can be generated from an ink composition describedherein by incorporating such a composition into a suitable printingapparatus (e.g., an inkjet printer) and generating an image onto asubstrate. Examples of suitable inkjet printers include thermalprinters, piezoelectric printers, continuous printers, and valve jetprinters. An image can be printed on any suitable substrate, such asplain papers, bonded papers, coated papers, transparency materials,textile materials, plastics, polymeric films, and inorganic substrates.

All publications, references, applications, and patents referred toherein are incorporated by reference in their entirety.

The following examples are illustrative and not intended to be limiting.

EXAMPLES Ink Evaluation

The inkjet ink compositions described in the following examples belowwere evaluated as follows.

The inkjet ink compositions were printed on paper using a Canon iP4000thermal inkjet printer. Each inkjet ink composition was loaded into aCanon compatible cartridge (available from Inkjet Warehouse) and printedwith the following printer settings: print quality: high; plain paper;grey scale; and no photo options selected. Images were printed onHewlett-Packard multi-purpose printing paper (HPMP) and Xerox 4200 plainpaper. Print properties of the resulting printed images were measured atvarious times after printing (particularly 5 minutes and 24 hours).

The optical density (OD) of the printed images was measured using eithera SpectroEye Gretag or X-rite 938 spectrophotometers. For bothinstruments, the following settings were used: Illumination at D65, 2degree Standard Observer, DIN density standard, white base set to Abs,and no filter. Results were reported as an average of OD values on thesetwo papers. For each paper, OD value was reported as an average of atleast three optical density measurements taken at two corners, and themiddle of a page.

Smear resistance (i.e., smear-fastness) was measured in a highlightsmear test (also referred to as the durability test) by using a yellowSharpie ACCENT Yellow Highlighters #25025 as follows. A single pass ordouble pass (two swipes, one on top of the other) of the highlighter ona non-printed portion of the paper was performed to establish areference value. Another single or double pass was then made across four2-mm wide stripes printed 3 mm apart. Using the SpectroEye, the opticaldensity (OD) value adjacent to the printed area for each swipe of thehighlighter was measured, along with the reference OD value. Thedifference between the reference OD value and the measured OD valueadjacent to the printed area (ΔOD) was the smear-fastness value.Usually, ΔOD values were recorded for tests from a single pass at 5minutes after printing and a double pass at 24 hours after printing. Thesmear-fastness (i.e., durability) was ranked as:

A=no or little smearing is found (i.e., when at least three of four ΔODvalues are no greater than 0.02, in which the four ΔOD values aremeasured from a single pass at 5 minutes after printing and a doublepass at 24 hours after printing on HPMP and Xerox 4200 papers);

B=a slight amount of smearing is observed (i.e., when four ΔOD valuesstay outside the requirements for ranking A and ranking C, in which thefour ΔOD values are measured from a single pass at 5 minutes afterprinting and a double pass at 24 hours after printing on HPMP and Xerox4200 papers); and

C=noticeable smearing is observed (i.e., when at least two of four ΔODvalues are no less than 0.11, in which the four ΔOD values are measuredfrom a single pass at 5 minutes after printing and a double pass at 24hours after printing on HPMP and Xerox 4200 papers).

For each inkjet ink composition, its jetting was evaluated by two tests.These two tests are described as follows:

Jetting Test I: Each inkjet ink composition was printed using a CanoniP4000 thermal inkjet printer to generate 10 pages of solid (i.e., 100%ink coverage) black blocks (size: 6.5 inch×9.5 inch) with the followingprinter settings: print quality: normal; plain paper; grey scale; and nophoto options selected. Images were printed on HPMP paper. These 10pages of solid black prints were evaluated as:

Good=No or little defects;

Fair=Some missing lines on most of these 10 pages;

Poor=Many missing lines on most of these 10 pages; and

Worst=Ink was unable to print using Canon iP4000 printer.

Jetting Test II: For each inkjet ink composition, a drop weight test wasalso performed on an HP45 thermal inkjet cartridge, which was filledwith the inkjet ink composition. A computer was used to control theselection of firing nozzles and the firing electrical parameters. Theink drops were collected and weighed. The average drop weight (ng) wasobtained by firing each ink for about 10-50 million drops in the sameconditions. The drop weight test results were evaluated as:

Good=the average drop weight was above 34 ng;

Fair=the average drop weight was between 30 and 34 ng; and

Poor=the average drop weight was below 30 ng.

Determination of the Molecular Weight of Polyurethanes

The molecular weights of the polyurethane in the Examples below weremeasured by a size exclusion chromatography as follows: A polyurethanewas first dissolved in a solvent mixture containing water,trifluoroacetic acid, and tetrahydrofuran. The polyurethane solution wasthen injected into a Plgel Mixed-D column. The mobile phase was 0.1 vol% of trifluoroacetic acid in tetrahydrofuran. The weight-averagemolecular weight of polyurethane and its molecular weight distributionwere determined from the comparison of the resulting data withpolystyrene standards with known molecular weights.

Determination of the Phosphorus Content (P % Wt) in Polyurethanes

The polyurethane samples containing bisphosphonate groups were firstdialyzed against deionized water by using a dialysis tube with anappropriate molecular weight cut off (i.e., MWCO) (e.g., Spectro/Por®Dialysis Membrane, MWCO 2 kD), or subjected to a diafiltration processwith an appropriate filtration cartridge (e.g., GE® ultrafiltration flowcartridge with a nominal molecular weight cutoff of 100K), to remove allunreacted bisphosphonate-containing reagents. These purifiedpolyurethane samples were then analyzed by ³¹P NMR against an externalstandard to determine the phosphorus content (P % wt relative to thetotal polyurethane solid).

Determination of the Acid Number of Polyurethanes

For the polyurethanes without a functional group described above (e.g.,a bisphosphonate group), its acid number (AN) was calculated by usingthe amounts of co-monomers that form the repeat units of formulae (I),(II), and (III) (hereinafter referred to as co-monomers I, II, and III)based on the following equation:AN=mole of co-monomer I×56.1 mgKOH×1000/(the total mass(g) of co-monomerI+co-monomer II+co-monomer III)

For the polyurethanes containing a functional group described above(e.g., a bisphosphonate group), its acid number was calculated by thefollowing equation:AN=mole of co-monomer I×56.1 mgKOH×1000/(the total mass(g) of co-monomerI+co-monomer II+co-monomer III)+P % wt/31×56.1 mgKOH×2×1000Preparation of Bisphosphonate-Modified Carbon Black Dispersion

In Examples 1-6 described below, the pigment used was a modified carbonblack (i.e., carbon black attached with at least one organic group), inwhich the organic group includes at least one geminal bisphosphonic acidgroup or salt thereof. This modified pigment can be prepared, forexample, by using the procedure described in U.S. Patent ApplicationPublication No. 20070100024. Examples 7 and 8 used unmodified carbonblacks.

ABBREVIATIONS AND COMMERCIAL SOURCES

TDI=toluene diisocyanate

DMPA=dimethylolpropionic acid (Bis-MPA™ from Perstorp)

DBTL=dibutyltin dilaurate

NMP=N-Methylpyrrolidone

KOH=potassium hydroxide

TEA=triethylamine

PEG600=a polyethylene glycol with a molecular weight of 600 g/mol

TMP=trimethylolpropane

SURFYNOL 465=a non-ionic surfactant from Air Products

ARCOL PPG-1000=Polypropylene glycol with a hydroxyl number of about 112mg KOH/g (from Bayer MaterialScience LLC)

FOMREZ 44-114U=a polyester diol with a hydroxyl number of about 114 mgKOH/g (from Chemtura)

OXYMER M112=a polycarbonate diol with a hydroxyl number of about 112 mgKOH/g (from Perstorp)

DURANOL-T5651=a polycarbonate diol with a hydroxyl number of about 110mgKOH/Wg (from Asahi Kasei Chemicals Corporation)

BP700=Carbon Black grade, BLACK PEARLS 700 (from Cabot Corporation)

The following Examples describe the preparation of NCO-terminatedprepolymer followed by the chain extension in water in the presence orabsence of reagents containing a functional group described above. Inthese Examples, the inkjet ink compositions containedbisphosphonate-modified carbon black dispersion and the polyurethanewith or without any functional group.

Example I Preparation of NCO-Terminated Prepolymer I

To a 1 liter cylindrical reactor, equipped with a temperature monitor, astirrer, a condenser, and a nitrogen gas line, were added 186.6 g ofARCOL PPG-1000, 20.66 g of DMPA and 41.3 g of NMP. After the content washeated to 100° C. under fast nitrogen flow, high vacuum was applied. Theclear, well mixed solution thus obtained was back flushed with nitrogenand then cooled to about 50-60° C. 62.7 g of TDI was then added to themixture dropwise via an addition funnel or a plastic syringe, while thetemperature was well controlled to remain below about 80° C. After a fewminutes, 0.22 g of DBTL was added. The reaction temperature was thenraised to about 80° C. and held for 3 hours. After the temperature wascooled to about 60-70° C., 460 mL of anhydrous acetone was added slowlyunder stirring. The prepolymer acetone solution was obtained and kept atabout 40° C. under nitrogen. The NCO % was determined by titration to be1.108. This batch of NCO-terminated prepolymer acetone solution wasdivided into several parts for the next step.

Preparation of Polyurethane Example IA (PU-IA)

Under stirring, about 90 g of the warm NCO-terminated prepolymer acetonesolution obtained above was added quickly via a syringe or an additionfunnel at room temperature to an aqueous solution containing about 200 gof deionized water, 3.1 g of sodium alendronate trihydrate, and 6.14 gof a 45 wt % KOH solution. The reaction mixture was kept stirringovernight, and then acetone was removed under vacuum. A final solutioncontaining a polyurethane having bisphosphonate groups was obtained:14.3% solid, Mw=22,600 g/mol, AN=47.1, P % wt=0.42.

Preparation of Polyurethane Comparative Example IB (PU-IB)

Under stirring, about 90 g of the warm NCO-terminated prepolymer acetonesolution obtained above was added quickly via a syringe or an additionfunnel at room temperature to an aqueous solution containing about 200 gof deionized water and 2.57 g of a 45 wt % KOH solution. The reactionmixture was kept stirring overnight, and then acetone was removed undervacuum. A final solution containing a polyurethane without anybisphosphonate group was obtained: 13.1% solid, Mw=55,700 g/mol, AN=32.

Preparation of Polyurethane Comparative Example IC (PU-IC)

Under stirring, about 90 g of the warm NCO-terminated prepolymer acetonesolution obtained was added quickly via a syringe or an addition funnelat room temperature to an aqueous solution containing about 200 g ofdeionized water, 1 g of diethanolamine, and 2.57 g of a 45 wt % KOHsolution. The reaction mixture was kept stirring overnight, and thenacetone was removed under vacuum. A final solution containing apolyurethane without any bisphosphonate group was obtained: 13.9% solid,Mw=18,000 g/mol, AN=32.

Ink Compositions and Their Test Results

The polyurethane example and comparative examples were used as additivesto make ink compositions using the formulation shown in Table 1. Theamounts listed are in weight percent of the final ink composition. Thepigment dispersions and polyurethanes are quoted on a solid basis. Thetest results of these ink compositions were summarized in Table 3.

The polyurethane of Example IA included bisphosphonate groups, while thepolyurethanes of Comparative Examples IB and IC did not include anybisphosphonate groups. In addition, the polyurethane of Example IA had ahigher acid number than that of the polyurethanes of ComparativeExamples IB and IC, and a relative low weight average molecular weightcompared to those of the polyurethanes of Comparative Examples IB andIC. As shown in Table 3, the ink composition containing the polyurethaneof Example IA exhibited superior overall performance (i.e., superiorjetting capability and similar or better image durability whilemaintaining high image optical density) compared to the ink compositionscontaining the polyurethanes of Comparative Examples IB and IC.

Example II Preparation of NCO-Terminated Prepolymer II

To a 1 liter cylindrical reactor equipped with a temperature monitor, astirrer, a condenser, and a nitrogen gas line were added 136.6 g ofARCOL PPG-1000, 20.9 g of DMPA and 41.8 g of NMP. After the content washeated to 100° C. under fast nitrogen flow, high vacuum was applied. Theclear, well mixed solution thus obtained was back flushed with nitrogenand then cooled to about 50-60° C. 61 g of TDI was added to the mixturedropwise via an addition funnel or a plastic syringe, while thetemperature was well controlled to remain below about 80° C. Thereaction temperature was then raised to about 80° C. and held for 4hours. After the temperature was cooled to about 60-70° C., 365 mL ofanhydrous acetone was added slowly under stirring. A polymer acetonesolution was obtained and kept at about 40° C. under nitrogen. The NCO %was determined by titration to be 2.209. This batch of NCO-terminatedprepolymer acetone solution was divided into several parts for the nextstep.

Preparation of Polyurethane Example IIA (PU-IIA)

Under stirring, about 90 g of the warm NCO-terminated prepolymer acetonesolution obtained above was added quickly via a syringe or an additionfunnel at room temperature to an aqueous solution contain about 200 g ofdeionized water, 6.2 g of sodium alendronate trihydrate, and 10.3 g of a45 wt % KOH solution. The reaction mixture was kept stirring overnight,and then acetone was removed under vacuum. A final solution containing apolyurethane having bisphosphonate groups was obtained: 18.0% solid,Mw=13,600 g/mol, AN=70.4, P % wt=0.84.

Preparation of Polyurethane Example IIB (PU-IIB)

Under stirring, about 90 g of the warm NCO-terminated prepolymer acetonesolution obtained above was added quickly via a syringe or an additionfunnel at room temperature to an aqueous solution containing about 200 gof deionized water, 6.2 g of sodium alendronate trihydrate, and 7.9 g ofa 45 wt % KOH solution. The reaction mixture was kept stirringovernight, and then acetone was removed under vacuum. A final solutioncontaining a polyurethane having bisphosphonate groups was obtained:19.1% solid, Mw=23,000 g/mol, AN=77.4, P % wt=1.03.

Preparation of Polyurethane Comparative Example IIC (PU-IIC)

Under stirring, about 90 g of the warm NCO-terminated prepolymer acetonesolution thus obtained was added quickly via a syringe or an additionfunnel at room temperature to an aqueous solution containing about 200 gof deionized water and 3.2 g of a 45 wt % KOH solution. The reactionmixture was kept stirring overnight, and then acetone was removed undervacuum. A final solution containing a polyurethane without anybisphosphonate group was obtained: 16.4% solid, Mw=127,000 g/mol, AN=40.

Ink Compositions and Their Test Results

The above polyurethane examples and comparative example were used asadditives to make ink compositions using the formulation shown inTable 1. The amounts listed are in weight percent of the final inkcomposition. The pigment dispersions and polyurethanes are quoted on asolid basis. The test results of these ink compositions were summarizedin Table 3.

The polyurethanes of Examples IIA and IIB included bisphosphonategroups, while the polyurethane of Comparative Example IIC did notinclude any bisphosphonate groups. In addition, the polyurethanes ofExamples IIA and IIB had higher acid numbers and lower weight averagemolecular weights than those of the polyurethane of Comparative ExampleIIC. As shown in Table 3, the ink compositions containing thepolyurethanes of Example IIA and IIB exhibited superior overallperformance (i.e., superior jetting capability and similar or betterimage durability while providing much higher image optical density)compared to the ink composition containing the polyurethane ofComparative Example IIC.

Example III Preparation of NCO-Terminated Prepolymer III

To a 1 liter cylindrical reactor equipped with a temperature monitor, astirrer, a condenser, and a nitrogen gas line were added 121.1 g ofARCOL PPG-1000, 34.5 g of DMPA, and 69.0 g of NMP. After the content washeated to 100° C. under fast nitrogen flow, high vacuum was applied. Theclear, well mixed solution thus obtained was back flushed with nitrogenand then cooled to about 50-60° C. 69.7 g of TDI was then added to themixture dropwise via an addition funnel or a plastic syringe, while thetemperature was well controlled to remain below about 80° C. After a fewminutes, 0.18 g of DBTL was added. The reaction temperature was thenraised to about 80° C. and held for 3 hours. After the temperature wascooled to about 60-70° C., 580 mL of anhydrous acetone was added slowlyunder stirring. A polymer acetone solution was obtained and kept atabout 40° C. under nitrogen. The NCO % was determined by titration to be0.889. 22.3 mL of TEA was then added to this batch of NCO-terminatedprepolymer acetone solution, followed by stirring for about 30 minute atabout 40° C. under nitrogen. The solution thus obtained was divided intoseveral parts for the next step.

Preparation of Polyurethane Example IIIA (PU-IIIA)

Under stirring, about 110 g of the warm NCO-terminated prepolymeracetone solution obtained above was added quickly via a syringe or anaddition funnel at room temperature to an aqueous solution contain about180 g of deionized water, 2.2 g of sodium alendronate trihydrate, and18.8 g of a 10 wt % KOH solution. The reaction mixture was kept stirringovernight, and then acetone was removed under vacuum. A final solutioncontaining a polyurethane having bisphosphonate groups was obtained:13.1% solid, Mw=46,000 g/mol, AN=81.5, P % wt=0.48.

Preparation of Polyurethane Comparative Example IIIB (PU-IIIB)

Under stirring, about 110 g of the warm NCO-terminated prepolymeracetone solution obtained above was added quickly via a syringe or anaddition funnel at room temperature to an aqueous solution containingabout 180 g of deionized water and 7.3 g of a wt % KOH solution. Thereaction mixture was kept stirring overnight, and then acetone wasremoved under vacuum. A final solution containing a polyurethane withoutany bisphosphonate group was obtained: 14.8% solid, Mw=71,700 g/mol,AN=64.

Ink Compositions and Their Test Results

The above polyurethane example and comparative example were used asadditives to make ink compositions using the formulation shown inTable 1. The amounts listed are in weight percent of the final inkcomposition. The pigment dispersions and polyurethanes are quoted on asolid basis. The testing results of these ink compositions weresummarized in Table 3.

The polyurethane of Example IIIA included bisphosphonate groups, whilethe polyurethane of Comparative Example IIIB did not include anybisphosphonate groups. In addition, the polyurethane of Example IIIA hada higher acid number and a lower weight average molecular weight thanthose of the polyurethane of Comparative Example IIIB. As shown in Table3, the ink composition containing the polyurethane of Example IIIAexhibited superior overall performance (i.e., superior jettingcapability and image durability while providing high image opticaldensity) compared to the ink composition containing the polyurethane ofComparative Example IIIB.

Example IV Preparation of NCO-Terminated Prepolymer IV

To a 1 liter cylindrical reactor equipped with a temperature monitor, astirrer, a condenser, and a nitrogen gas line, were added 145.0 g ofFOMREZ 44-114U, 27.2 g of DMPA, and 54.4 g of NMP. After the content washeated to 100° C. under fast nitrogen flow, high vacuum was applied. Theclear, well mixed solution thus obtained was back flushed with nitrogenand then cooled to about 50-60° C. 64.5 g of TDI was then added to themixture dropwise via an addition funnel or a plastic syringe, while thetemperature was well controlled to remain below about 80. After a fewminutes, 0.19 g of DBTL was added. The reaction temperature was thenraised to about 80° C. and held for 3 hours. After the temperature wascooled to about 60-70° C., 385 mL of anhydrous acetone was added slowlyunder stirring. A prepolymer acetone solution was obtained and kept atabout 40° C. under nitrogen. The NCO % was determined by titration to be0.934. This batch of NCO-terminated prepolymer acetone solution wasdivided into several parts for the next step.

Preparation of Polyurethane Example IVA (PU-IVA)

Under stirring, about 90 g of the warm NCO-terminated prepolymer acetonesolution obtained above was added quickly via a syringe or an additionfunnel at room temperature to an aqueous solution containing about 200 gof deionized water, 2.73 g of sodium alendronate trihydrate, and 5.93 gof a 45 wt % KOH solution. The reaction mixture was kept stirringovernight, and then acetone was removed under vacuum. A final solutioncontaining a polyurethane having bisphosphonate groups was obtained:16.9% solid, Mw=16,000 g/mol, AN=58.8, P % wt=0.30.

Preparation of Polyurethane Comparative Example IVB (PU-IVB)

Under stirring, about 90 g of the warm NCO-terminated prepolymer acetonesolution obtained above was added quickly via a syringe or an additionfunnel at room temperature to an aqueous solution containing about 200 gof deionized water and 3.8 g of a 45 wt % KOH solution. The reactionmixture was kept stirring overnight, and then acetone was removed undervacuum. A final solution containing a polyurethane without anybisphosphonate group was obtained: 16.5% solid, Mw=23,800 g/mol, AN=48.

Ink Compositions and Their Test Results

The above polyurethane example and comparative example were used asadditives to make ink compositions using the formulation shown in Table2. The amounts listed are in weight percent of the final inkcomposition. The pigment dispersions and polyurethanes are quoted on asolid basis. The test results of these ink compositions were summarizedin Table 3.

The polyurethane of Example IVA included bisphosphonate groups, whilethe polyurethane of Comparative Example IVB did not include anybisphosphonate groups. In addition, the polyurethane of Example IVA hada higher acid number and a lower weight average molecular weight thanthose of the polyurethane of Comparative Example IVB. As shown in Table3, the ink composition containing the polyurethane of Example IVAexhibited superior overall performance (i.e., superior jettingcapability and similar image durability while providing much higherimage optical density) compared to the ink composition containing thepolyurethane of Comparative Example IVB.

Example V Preparation of NCO-Terminated Prepolymer V

To a 1 liter cylindrical reactor equipped with a temperature monitor, astirrer, a condenser, and a nitrogen gas line, were added 146.2 g ofOXYMER M112, 41.5 g of DMPA, and 83.0 g of NMP. After the content washeated to 100° C. under fast nitrogen flow, high vacuum was applied. Theclear, well mixed solution thus obtained was back flushed with nitrogenand then cooled to about 50-60° C. 83.6 g of TDI was then added to themixture dropwise via an addition funnel or a plastic syringe, while thetemperature was well controlled to remain below about 80° C. Thereaction temperature was then raised to about 80° C. and held for 3hours. After the temperature was cooled to about 60-70° C., 1270 mL ofanhydrous acetone was added slowly under stirring. A prepolymer acetonesolution was obtained and kept at about 40° C. under nitrogen. The NCO %was determined by titration to be 1.458. 40.1 mL of TEA was then addedto this batch of NCO-terminated prepolymer acetone solution, followed bystirring for about 30 minute at about 40° C. under nitrogen. Thesolution thus obtained was divided into several parts for the next step.

Preparation of Polyurethane Example VA (PU-VA)

Under stirring, about 180 g of the warm NCO-terminated prepolymeracetone solution obtained above was added quickly via a syringe or anaddition funnel at room temperature to an aqueous solution containingabout 250 g of deionized water, 4.1 g of sodium alendronate trihydrate,and 4.7 g of a 45 wt % KOH solution. The reaction mixture was keptstirring overnight, and then acetone was removed under vacuum. A finalsolution containing a polyurethane having bisphosphonate groups wasobtained: 14.1% solid, Mw=25,300 g/mol, AN=87.4, P % wt=0.65.

Preparation of Polyurethane Comparative Example VB (PU-VB)

Under stirring, about 180 g of the warm NCO-terminated prepolymeracetone solution obtained above was added quickly via a syringe or anaddition funnel at room temperature to an aqueous solution containingabout 250 g of deionized water. The reaction mixture was kept stirringovernight, and then acetone was removed under vacuum. A final solutioncontaining a polyurethane without any bisphosphonate group was obtained:11.6% solid, Mw=53,700 g/mol, AN=64.

Preparation of Polyurethane Comparative Example VC (PU-VC)

Under stirring, about 180 g of the warm NCO-terminated prepolymeracetone solution obtained above was added quickly via a syringe or anaddition funnel to a room temperature to an aqueous solution containingabout 250 g of deionized water and 1.3 g of diethanolamine. The reactionmixture was kept stirring overnight, and then acetone was removed undervacuum. A final solution containing a polyurethane without anybisphosphonate group was obtained: 14.4% solid, Mw=16,600 g/mol, AN=64.

Ink Compositions and their Test Results

The above polyurethane example and comparative examples were used asadditives to make ink compositions using the formulation shown in Table2. The amounts listed are in weight percent of the final inkcomposition. The pigment dispersions and polyurethanes are quoted on asolid basis. The test results of these ink compositions were summarizedin Table 3.

The polyurethane of Example VA included bisphosphonate groups, while thepolyurethanes of Comparative Examples VB and VC did not include anybisphosphonate groups. In addition, the polyurethane of Example VA had ahigher acid number than those of the polyurethanes of ComparativeExamples VB and VC, and a relatively low weight average molecular weightcompared to those of the polyurethanes of Comparative Examples VB andVC. As shown in Table 3, the ink composition containing the polyurethaneof Example VA exhibited superior overall performance (i.e., superiorjetting capability, image durability, and image optical density)compared to the ink compositions containing the polyurethanes ofComparative Examples VB and VC.

Example VI Preparation of NCO-Terminated Prepolymer VI

To a 1 liter cylindrical reactor equipped with a temperature monitor, astirrer, a condenser, and a nitrogen gas line, were added 139.8 g ofDURANOL-T5651, 26.1 g of DMPA, and 52.2 g of NMP. After the content washeated to 100° C. under fast nitrogen flow, high vacuum was applied. Theclear, well mixed solution thus obtained was back flushed with nitrogenand then cooled to about 50-60° C. 61.8 g of TDI was then added to themixture dropwise via an addition funnel or a plastic syringe, while thetemperature was well controlled to remain below about 80° C. After a fewminutes, 0.18 g of DBTL was added. The reaction temperature was thenraised to about 80° C. and held for about 2 hours. After the temperaturewas cooled to about 60° C., 370 mL of anhydrous acetone was added slowlyunder stirring. A prepolymer acetone solution was obtained and kept atabout 40° C. under nitrogen. The NCO % was determined by titration to be1.139. This batch of NCO-terminated prepolymer acetone solution wasdivided into several parts for the next step.

Preparation of Polyurethane Example VIA (PU-VIA)

Under stirring, about 90 g of the warm NCO-terminated prepolymer acetonesolution obtained above was added quickly via a syringe or an additionfunnel at room temperature to an aqueous solution containing about 200 gof deionized water, 3.33 g of sodium alendronate trihydrate, and 34.5 gof a 10 wt % KOH solution. The reaction mixture was kept stirringovernight, and then acetone was removed under vacuum. A final solutioncontaining a polyurethane having bisphosphonate groups was obtained:12.0% solid, Mw=23,400 g/mol, AN=63.8, P % wt=0.44.

Preparation of Polyurethane Comparative Example VIB (PU-VIB)

Under stirring, about 90 g of the warm NCO-terminated prepolymer acetonesolution obtained above was added quickly via a syringe or an additionfunnel at room temperature to an aqueous solution containing about 200 gof deionized water and 17.3 g of a 10 wt % KOH solution. The reactionmixture was kept stirring overnight, and then acetone was removed undervacuum. A final solution containing a polyurethane without anybisphosphonate group was obtained: 14.2% solid, Mw=51,600 g/mol, AN=48.

Ink Compositions and Their Test Results

The above polyurethane example and comparative example were used asadditives to make ink compositions using the formulation shown in Table2. The amounts listed are in weight percent of the final inkcomposition. The pigment dispersions and polyurethanes are quoted on asolid basis. The test results of these ink compositions were summarizedin Table 3.

The polyurethane of Example VIA included bisphosphonate groups, whilethe polyurethane of Comparative Example VIB did not include anybisphosphonate groups. In addition, the polyurethane of Example VIA hada higher acid number and a lower weight average molecular weight thanthose of the polyurethane of Comparative Example VIB. As shown in Table12, the ink composition containing the polyurethane of Example VIAexhibited superior overall performance (i.e., superior jettingcapability and image durability while maintaining high image opticaldensity) compared to the ink composition containing the polyurethane ofComparative Example VIB.

TABLE 1 Comp Ex Comp Ex Comp Ex Comp Ex Component Ex IA IB IC Ex IIA ExIIB IIC Ex IIIA IIIB Black 4% 4% 4% 4% 4% 4% 4% 4% Dispersion (pigment)PU-IA 1% PU-IB 1% PU-IC 1% PU-IIA 2% PU-IIB 2% PU-IIC 2% PU-IIIA 1%PU-IIIB 1% Glycerol 5% 5% 5% 5% 5% 5% 5% 5% PEG600 5% 5% 5% 5% 5% 5% 5%5% TMP 3% 3% 3% 3% 3% 3% 3% 3% Surfynol ® 0.1%   0.1%   0.1%   0.1%  0.1%   0.1%   0.1%   0.1%   465 Water balance balance balance balancebalance balance balance balance

TABLE 2 Comp Ex Comp Ex Comp Ex Comp Ex Component Ex IVA IVB Ex VA VB VCEx VIA VIB Black 4% 4% 4% 4% 4% 4% 4% Dispersion (pigment) PU-IVA 1%PU-IVB 1% PU-VA 1% PU-VB 1% PU-VC 1% PU-VIA 2% PU-VIB 2% Glycerol 5% 5%5% 5% 5% 5% 5% PEG600 5% 5% 5% 5% 5% 5% 5% TMP 3% 3% 3% 3% 3% 3% 3%Surfynol ® 0.1%   0.1%   0.1%   0.1%   0.1%   0.1%   0.1%   465 Waterbalance balance balance balance balance balance balance

TABLE 3 PU % Jetting Test Jetting Test Durability Inks in ink OD IRanking II Ranking Ranking Ex IA 1 1.46 Good Good B Comp Ex IB 1 1.40Fair Poor B Comp Ex IC 1 1.45 Good Fair C Ex IIA 2 1.47 Good Good B ExIIB 2 1.44 Good Good A Comp Ex IIC 2 1.21 Poor Poor A Ex IIIA 1 1.51Good Good A Comp Ex IIIB 1 no Worst Poor no value* ranking* Ex IVA 11.48 Good Good A Comp Ex IVB 1 1.32 Fair Good A Ex VA 1 1.45 Good Fair BComp Ex VB 1 no Worst Poor no value* ranking* Comp Ex VC 1 1.34 PoorPoor C Ex VIA 2 1.45 Good Good A Comp Ex VIB 2 1.41 Fair Poor A *Sincesuch example was unable to print in iP4000 printer, both OD measurementand durability test were unable to be performed.

Example VII Preparation of Carbon Black Dispersion by Using PU-IVA(PU-IVA-BP700-1)

First, about 55 g of a polyurethane dispersion (i.e., containing 16.4%PU-IVA solids) was diluted with 200 g of DI water. After about 18 gcarbon black BP700 was added, the resultant mixture stirred rapidly toincorporate the dry powder. This mixture was then sonicated at about5-12° C. using a Misonix probe sonicator for about 1.5 hours to afford ablack dispersion with a mean particle size of about 150 nm (determinedby using a Microtrac® Particle Size Analyzer). The disperison wascentrifuged at 2,500 G for about 10 minutes, and then decanted toisolate the product. A final solution containing 9.75%polyurethane-dispersed carbon black was obtained.

Ink Composition and its Test Results

The pigment dispersion was used as a dispersant to make an inkcomposition using the formulation shown in Table 4. The amounts listedare in weight percent of the final ink composition. The pigmentdispersions and polyurethanes are quoted on a solid basis. The testresults of this ink composition were summarized in Table 5.

As shown in Table 5, the ink composition containing the polyurethane ofExample VII exhibited excellent overall performance (i.e., excellentjetting capability and image durability).

Example VIII Preparation of Carbon Black Dispersion by Using PU-IVA(PU-IVA-BP700-2)

First, about 41 g of a polyurethane dispersion (i.e., containing 16.4%PU-IVA solids) was diluted with 200 g of DI water. After about 20 gcarbon black BP700 was added, the resultant mixture was stirred rapidlyto incorporate the dry powder. This mixture was then sonicated at about5-12° C. using a Misonix probe sonicator for about 1.5 hours to afford ablack dispersion with a mean particle size of about 150 nm (determinedby using a Microtrac® Particle Size Analyzer). The dispersion wascentrifuged at 2,500 G for about 10 minutes, and then decanted toisolate the product. A final solution containing 9.52%polyurethane-dispersed carbon black was obtained.

Ink Composition and Its Test Results

The pigment dispersion was used as a dispersant to make an inkcomposition using the formulation shown in Table 4. The amounts listedare in weight percent of the final ink composition. The pigmentdispersions and polyurethanes are quoted on a solid basis. The testresults of this ink composition were summarized in Table 5.

As shown in Table 5, the ink composition containing the polyurethane ofExample VIII exhibited excellent overall performance (i.e., excellentjetting capability and image durability).

TABLE 4 Component Ex VII Ex VIII PU-IVA-BP700-1 6% PU-IVA-BP700-2 5%Glycerol 5% 5% PEG600 5% 5% TMP 3% 3% Surfynol ® 465 0.1%  0.1%  Waterbalance balance

TABLE 5 Inks OD Jetting Ranking Durability Ranking Ex VII 1.24 B A ExVIII 1.31 B A

Other embodiments are in the claims.

What is claimed is:
 1. A composition, comprising: a polyurethane; apigment; and a liquid vehicle, wherein the polyurethane comprises: afirst comonomer repeat unit that comprises a hydrophilic group, and afunctional group different from the hydrophilic group, the functionalgroup comprising (CH₂)_(n)C(R)(PO₃H₂)₂ or an ester or salt thereofwherein the functional group is an end group of the polyurethane, andwherein n is 0-9 and R is H, R_(a), OR_(a), SR_(a), or NR_(a)R_(b), inwhich each of R_(a) and R_(b), independently, being H, C₁-C₁₀ alkyl, oraryl.
 2. The composition of claim 1, wherein the pigment comprisescarbon black.
 3. The composition of claim 1, wherein the liquid vehiclecomprises an aqueous solution.
 4. A polyurethane, comprising: acomonomer repeat unit of formula (IV) or (V):—N(R₉)—R₄—N(R₆)—R₅—N(R₁₀)—  (IV)or—N(R₉)—R₄—C(R₇R₈)—R₅—N(R₁₀)—  (V) wherein each of R₄ and R₅,independently, is a bond, C₁-C₁₀ alkylene, C₃-C₂₀ cycloalkylene, C₃-C₂₀heterocycloalkylene, arylene, or heteroarylene, each of which beingoptionally substituted with C₁-C₁₀ alkyl or aryl, provided that at leastone of R₄ and R₅ is not a bond; R₆ is (CH₂)_(n)C(R)(PO₃H₂)₂ or an esteror salt thereof, in which n is 0-9 and R is H, R_(a), OR_(a), SR_(a), orNR_(a)R_(b), each of R_(a) and R_(b), independently, being H, C₁-C₁₀alkyl, or aryl; each of R₇ and R₈, independently, is H, R_(c), OR_(c),SR_(c), NR_(c)R_(d), PO₃H₂ or an ester or salt thereof, or(CH₂)_(m)C(R′)(PO₃H₂)₂ or an ester or salt thereof, in which m is 0-9and R′ is H, R_(c), OR_(c), SR_(c), or NR_(c)R_(d), each of R_(c) andR_(d), independently, being H, C₁-C₁₀ alkyl, or aryl, provided that, ifneither of R₇ and R₈ is (CH₂)_(m)C(R′)(PO₃H₂)₂ or an ester or saltthereof, both of R₇ and R₈ are PO₃H₂ or an ester or salt thereof; andeach of R₉ and R₁₀, independently, is H, C₁-C₁₀ alkyl, or aryl.
 5. Acomposition, comprising: the polyurethane of claim 4; and a liquidvehicle.
 6. The composition of claim 1, wherein the functional groupcomprises a partial salt of (CH₂)_(n)C(R)(PO₃H₂)₂, and the partial saltcomprises an anion formed from (CH₂)_(n)C(R)(PO₃H₂)₂ and a cationselected from the group consisting of Li⁺, Na⁺, K⁺, Cs⁺, or N(R_(c))₄ ⁺,in which R_(c) is H, C₁-C₁₀ alkyl, or aryl.
 7. The composition of claim1, wherein the functional group comprises a partial salt containing K⁺and an anion formed from (CH₂)_(n)C(R)(PO₃H₂)₂.
 8. The composition ofclaim 1, wherein n is 1-3 and R is OR_(a).
 9. The composition of claim1, wherein n is 3 and R is OH.
 10. The composition of claim 1, whereinthe polyurethane comprises two functional groups that comprise(CH₂)_(n)C(R)(PO₃H₂)₂ or an ester or salt thereof, each of which is anend group of the polyurethane.
 11. The composition of claim 1, whereinthe polyurethane comprises at least about 0.1 wt % phosphorus.
 12. Thecomposition of claim 1, wherein the hydrophilic group comprises acarboxylic acid group, a sulfonic acid group, a phosphonic acid group, ahydroxyl group, a polyether group, or a salt thereof.
 13. Thecomposition of claim 1, wherein the first comonomer repeat unit is offormula (I):—O—R₁—O—  (I), in which R₁ is C₁-C₁₀ alkylene, C₃-C₂₀ cycloalkylene,C₃-C₂₀ heterocycloalkylene, arylene, heteroarylene, or C₁-C₂₀alkylarylene, each of which is substituted with the hydrophilic groupand optionally further substituted with C₁-C₁₀ alkyl or aryl.
 14. Thecomposition of claim 13, wherein R₁ is C₁-C₁₀ alkylene substituted witha carboxylic acid or a salt thereof.
 15. The composition of claim 13,wherein R₁ is CH₂C(CH₃)(COOH)CH₂ or a salt thereof.
 16. The compositionof claim 1, wherein the first comonomer repeat unit is at least about 1%of the total weight of the polyurethane.
 17. The composition of claim 1,wherein the polyurethane further comprises a second comonomer repeatunit of formula (II):—C(O)—NH—R₂—NH—C(O)—  (II), in which R₂ is C₁-C₁₀ alkylene, C₃-C₂₀cycloalkylene, C₃-C₂₀ heterocycloalkylene, arylene, heteroarylene, or acombination thereof, each of which is optionally substituted with C₁-C₁₀alkyl or aryl.
 18. The composition of claim 17, wherein R₂ is C₁-C₁₀alkylene, C₃-C₂₀ cycloalkylene, arylene, or a combination thereof. 19.The composition of claim 17, wherein R₂ is hexamethylene, phenyleneoptionally substituted with methyl, cyclohexylene optionally substitutedwith methyl,


20. The composition of claim 1, wherein the polyurethane furthercomprises a third comonomer repeat unit of formula (III):—O—R₃—O—  (III), wherein R₃ comprises C₁-C₁₀ alkylene, C₃-C₂₀cycloalkylene, C₃-C₂₀ heterocycloalkylene, arylene, heteroarylene, apolyether moiety, a polyester moiety, a polycarbonate moiety, apolyacetal moiety, a polythioether moiety, a polyester amide moiety, apolyacrylate moiety, a polyolefin moiety, a polyalkylsiloxane moiety, ora mixture thereof.
 21. The composition of claim 20, wherein R₃ comprisesa polypropylene glycol moiety, a polytetramethyleneoxide moiety, apoly(butylene adipate) moiety, a poly(hexamethylene adipate) moiety, apolycarbonate moiety prepared from 2-butyl-2-ethylpropyl diol, apolycarbonate moiety prepared from a mixture of 1,5-pentanediol and1,6-hexanediol.
 22. The composition of claim 1, wherein the polyurethanehas an acid number of at least about
 25. 23. The composition of claim 1,wherein the polyurethane has a weight average molecule weight of atleast about 10,000 g/mol.
 24. The composition of claim 1, wherein thepolyurethane is from about 0.1% to about 15% of the total weight of thecomposition.